Diagnostic Aspects of a Bacillus Calmette-Guërin (BCG) Infection Following Intravesical Treatment for Bladder Cancer.

BACKGROUND: Bacillus Calmette-Guérin (BCG) infection is a rare complication of intravesical immunotherapy for bladder cancer. Distinguishing Mycobacterium bovis BCG from other Mycobacterium tuberculosis complex members is crucial due to intrinsic drug resistance.

METHODS: We report a case of BCG infection following intravesical immunotherapy and propose three laboratory clues.

RESULTS: White, spreading umbonate colony morphology; negative M. tuberculosis protein 64 (MPT-64) antigen test; and nearly identical cycle threshold values for insertion sequence 6110 (IS6110) and internal transcribed spacer targets in real-time PCR strongly suggest BCG infection.

CONCLUSIONS: These findings could facilitate the rapid identification of M. bovis BCG and appropriate treatments.